One of the biggest issues that affects England’s forests and urban green spaces is the Dutch elm disease or simply DED. It exclusively affects elm trees is caused by a three species of ascomycete microfungi (Ophiostoma ulmi, Ophiostoma himal-ulmi, and Ophiostoma novo-ulmi) that propagates itself through bark beetles. The disease traces its roots to Asia where it unintentionally spread to Oceania, Europe and the Americas where it has drastically reduced the population of elm trees. In the UK alone, more than 60 million elms have been infected and killed by it according to the Woodland Trust. Hence, the affliction is a major problem that has the ability to upset the balance within any given ecosystem where any species of elm flourishes.
Fortunately, since elms are living beings, they also have a version of an immune system. As such, they can naturally fight the disease through camouflage or by producing chemicals which keep beetles away by making their bark distasteful for them. Moreover, the trees also employ numerous other methods to prevent themselves from succumbing to DED. Even so, human intervention is still often necessary to save a tree because of the aggressive nature of the condition.
Dutch elm disease first introduces itself by withering away the leaves on an infected tree’s canopy during the summer months. Following that, the mentioned problem spreads downwards until large branches completely die. Soon enough, the roots start to decay because of the absence of nutrients that’s caused by the loss of leaves and important branches. Once that happens, it won’t be long before the infected tree succumbs to its illness and passes away. Nonetheless, a few species of elm don’t immediately fall to their demise once DED reaches their roots. Instead, they repeatedly put up suckers which thrive for about fifteen years before nature ultimately takes its course.
Since the first outbreaks of the disease in America and Europe during the 20th century, arborists have come up with several measures to eradicate it and contain its spread. The first thing people did was to prune and burn the parts of the tree which were known to be infected. Sadly, the method didn’t gain popularity due to the fact that performing it was quite expensive. Chemicals were then soon employed to get rid of the disease. However, the substances which people used at the time proved to be harmful towards animals like birds that rely on elms. Thankfully, some effective and safe fungicides were invented as the years went by. In addition to that, advancements in technology by the University of Amsterdam has brought about a new vaccine called Dutch Trig which is exceptional at completely keeping healthy trees away from the disease.
Nowadays, the Conservation Foundation has begun an active effort to propagate and distribute clones of the surviving indigenous elm trees in the UK. Because of that, the dwindled population of elms in the country is now slowly increasing once again. Despite that, it will probably take several decades before things return to normal as some areas still remain to be hotspots for DED.